June 27, 1878] 



NATURE 



229 



REAL BROWN BREAD 



NOTWITHSTANDING the labours of chemist and 

 physiologist, the exact composition and nutritive 

 value of the several products obtained in milling wheat 

 have not been thoroughly determined. That fine flour 

 contains less nitrogen, and leaves, when burnt, less ash 

 than biscuit flour, middlings, or any variety of bran, is 

 well known. The percentages of starch, of the mixture 

 of cellulose and lignose known as "fibre," and of fat, in 

 several series of samples of mill-products, have been 

 ascertained. Moreover, there have been made many 

 minute analyses of the ash of wheat and of the prepara- 

 tions derived from it. But we are still somewhat in the 

 dark concerning both the chemical and physiological 

 aspects of what may justly be regarded as the central 

 feature of the problem under discussion. For we are not 

 sure of the nature of the nitrogen compounds which 

 exist in the several distinct parts of the grain of wheat ; 

 nor do we know how far the phosphates and such nitro- 

 gen compounds as may be ranked with the true albu- 



Flour. 

 C 



minoids can be digested when intimately associated with 

 fibre. Then, too, the mechanical condition of these 

 coarser products from the milling of wheat is of consider- 

 able moment in estimating their actual value as nutrients. 



Before endeavouring to reach some conclusion as to the 

 comparative merits of white bread, brown bread, and 

 whole-meal bread, I will offer in as compact a form as 

 possible the more important and incontrovertible data 

 which must form the starting-point of the discussion. 



Firstly as to variations in composition in the grain 

 itself. These variations, chiefly affecting the percentage 

 of nitrogen, depend upon hereditary qualities in different 

 strains of the wheat-plant ; upon climate and season ; 

 and, to some extent, but not so largely as is often stated, 

 upon cultivation, soil, and manure. The hard translucent 

 wheats, blh durs et glacis, of high specific gravity, about 

 1*41, and, owing to their lengthened and wrinkled shape, 

 of low weight per bushel, these wheats are rich in nitro- 

 gen. The soft opaque wheats, of less specific gravity, 

 about I "38, and, owing to their rounded and plump form, 

 of high weight per bushel, these are poor in nitrogen. 



Brak. 



Nitrogen °,', 



Ash °, 



Nitrogen */, 



The hard wheats grown in Poland, in Southern Russia, 

 in Italy, and in Auvergne, are used in the manufacture of 

 macaroni, vermicelli, semohna, and pates d'ltalie. The 

 softer and more starchy wheats are especially appropriate 

 for the production of fine white flour. According to the most 

 recent analyses, the percentage of nitrogen in different 

 varieties and samples of air-dry wheat may range from 

 i"3 up to 2'5 — numbers corresponding to 8*23 and 15*83, 

 respectively, of gluten or flesh-forming substances. But 

 the same variety of wheat may give a grain having 3 per 

 cent, more gluten in a bad season than when matured in 

 a fine summer. More than this, one may select from the 

 same field, the same plant, or even the same ear, indi- 

 vidual grains which shall show quite as wide a variation 

 in gluten, as that just cited. For instance, a sample of 

 Hallett's white rough-chaffed wheat of the harvest of 

 . 1865 contained many dense and translucent homy grains 

 having I3'2 per cent, of gluten, while the white opaque 

 soft grains from the same sample contained but 9*6 per 

 rent. 



It will simplify the consideration of the chemistry of 



mill-products if we confine our attention mainly to the 

 nitrogen and ash of the grain. The following diagram 

 represents the percentages of these two substances in a 

 series of flours and brands derived from a good sample of 

 English soft wheat. The figures are based in great 

 measure upon the analyses made at Rothamsted by Dr. 

 Gilbert. The mill-products termed A, B, C, are derived 

 mainly from the central portion of the grain, and con- 

 stitute "fine flour;" D is a biscuit flour known as "tail- 

 ings ; " E is intermediate between flour and bran, and 

 goes under the name of "middlings;" F is "coarse 

 sharps," G "fine pollard," H "coarse pollard," and I "long 

 bran." K, or thin bran, is a product obtained in the 

 process of decorticating wheat by attrition; while L is 

 separated from the grain by moistening and then rubbing 

 it, as in the method devised by M^ge Mouri^s. These 

 two latter products may legitimately find a place in the 

 series, since they represent the last terms as we proceed 

 towards the outer coats of the grain. 



The above table explains itself ; we would remark 

 merely that both nitrogen and ash are lowest in the four 



